Chlorine (Cl.sub.2) is a widely used chemical. It is used in laundry bleach, swimming pool chemicals, plastics (e.g., polyvinylchloride), insecticides, refrigerants, lubricant additives, chlorinated solvents, and many other products. Although a valuable and popular chemical, chlorine is a very hazardous toxic substance. Chlorine can burn eyes, sinuses, throat, and lungs, and prolonged exposure at high concentration can cause death.
While chlorine is a hazardous chemical, its hazards are well known, and reliable procedures and apparatuses have been developed over the years to handle and work with chlorine safely. Chlorine is usually sold by manufacturers in bulk quantities to various distributors who package and ship the chlorine, often in ton capacity tanks. The ton tanks are usually made of steel and are lifted by jib cranes or hoists.
A ton tank holds one ton of liquid chlorine. The chlorine does not completely fill the tank, as space must be allowed for expansion of the liquid, and a considerable volume of the tank contains chlorine gas above the liquid level The tank is about 30 inches in diameter and 811/2 inches long. Its weight when empty is approximately 1,550 pounds. Generally, the ton container is equipped with two valves, an upper valve for discharging gaseous chlorine and a lower valve for discharging liquid chlorine.
A leak in a valve can be a serious hazard. Liquid chlorine evaporates extremely rapidly and expands to about 460 times its original volume. One pound of liquid chlorine will expand to 5 cubic feet of gas. Thus, even a very small leak is potentially dangerous. Furthermore, chlorine is a highly reactive chemical that reacts with most materials to form other chemical compounds, and these reactions can be violent. For example, chlorine will react with water (moisture in the air) to form hydrochloric and hypochlorous acids which are very corrosive. Further, in the presence of oils, greases, or other hydrocarbons, chlorine can cause ignition, produce toxic smoke, and form residues that can clog systems.
The valves of the tank are usually protected during transport and storage with a valve protection hood. The valve protection hood is a hemispherical structure having a surrounding flange at its opening, and the surrounding flange has flange openings. The flange openings are designed to receive retaining straps located on the tank. For installation of the valve protection hood, the protection hood is rotated after the flange openings receive the retaining straps on the tank, so that the hood is secured to the tank via the straps holding to the flange. The reverse procedure is used for removing the hood. Further, finger holes are usually provided on the hood for facilitating rotation of the hood.
When a leak occurs in a chlorine tank, a full-faced self-contained breathing apparatus, airline respirator, or the like must be worn by those persons attempting to repair the leak. A leaking chlorine ton tank is positioned so that the leak is in the uppermost part of the tank. This positioning allows the chlorine to escape as a gas rather than as a liquid, which makes a big difference in the amount of chlorine released to the atmosphere. A leak around the valve stem of the leaking valve can often be stopped by closing the valve or tightening the packing gland nut. For a leak at the valve discharge outlet, the leak can often be stopped by replacing the gasket in the adaptor connection. Moreover, pinhole leaks in the end wall of the tank can sometimes be stopped by driving a hardwood peg or metal drift pin into the leak hole. However, if a leak occurs at the threads near the base of a valve, the leak must be stopped by using an emergency capping kit. Several emergency capping kits are known in the industry and are commercially available. They are all similar to an extent.
For purposes of discussion, an example of such a conventional emergency capping apparatus is shown in FIG. 1. The emergency capping apparatus 9 of FIG. 1 is manufactured by Indian Springs, Inc., New York, U.S.A., and is known as the Ton Container Emergency Capping Kit B. The capping apparatus 9 is a very complex device and requires training for learning how to properly install it on a ton tank 11. The capping kit 9 essentially comprises a hood 23 for placing about a leaking tank valve 14a, as an example, an elongated C-shaped brace member 24 which is placed across the rim 13 of the tank 11 over the leaking tank valve 14a via jack screws 15a, 15b and adjusting screws 17a-17d, an adjustable cap screw 26a passing through a threaded aperture 27a in the brace member 24 to exert force against the hood 23, and a gasket 29 at the base of the hood 23 for helping to seal the leaking tank valve 14a within the hood 23.
Although adequate for stopping chlorine leaks, the prior art capping apparatuses, as exemplified by the capping apparatus 9 of FIG. 1, suffer from various problems and disadvantages. Most have many assembly pieces and are complex, as is very apparent by examination of FIG. 1. Most require more than one person to install as a result of the many pieces. Further, most can only cap one leaking valve, not two leaking valves. Specifically, referring to FIG. 1, two of the hoods 23 cannot be placed side by side to prevent leaking from both of tank valves 14a, 14b because the gaskets 29 would interfere with and obstruct each other. In addition, the capping apparatuses must be installed while wearing a gas-tight, Level-A, fully encapsulated suit which makes the task even much more difficult. Oftentimes, it can take a half an hour to install a prior art capping apparatus, such as that shown in FIG. 1.
Thus, a heretofore unaddressed need exists in the industry for a capping apparatus for stopping a chlorine leak in a valve of a tank which is simpler in design, which takes only a single person to install, which reduces the amount of time necessary for installation, and which is capable of sealing more than one leaking valve.